This section is intended to provide a background or context to the invention disclosed below. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise explicitly indicated herein, what is described in this section is not prior art to the description in this application and is not admitted to be prior art by inclusion in this section.
3GPP RAN2 has started a Study Item (SI) on single cell point-to-multipoint (SC-PTM) transmission mode. The feature is intended to provide means for multicasting service data to a formed group of UEs on a per cell basis. It is assumed that the MBMS architecture will be re-used as much as possible. The services/applications are running in a group communication server or application server, GCS-AS, which may reside out of the mobile network.
Group services may be used for public safety use cases or mission critical push-to-talk (MCPTT) service, but not limited to those; also commercial applications, for example, vehicular communication or non-public safety may be supported.
The defined group of UEs for a service is tracked and their location continuously updated in order to be able to support service continuity. The UE may be RRC connected or the UE could be idle.
The UE re-selections in idle are not normally known to the network unless the UE moves from the tracking area to another where a tracking area update (TAU) procedure is needed. If the SC-PTM service is available for idle mode UEs, and as the SC-PTM by definition is configured on a per cell basis, the network does not have sufficient information to initiate required actions if a UE of a SC-PTM group moves out of the cell coverage. That is, the network does not have sufficient information for reselecting another cell.
Accordingly, there is a need for enhancing communication to allow efficient tracking for all UEs within a group and thereby provide desired network support service continuity.
The following abbreviations, which may be found in the specification and/or the drawing figures, are defined as follows:
3GPP third generation partnership project
CN Core network
GW Gateway
HSS Home subscription server
M2M Machine-to-machine
MBMS Multimedia Broadcast Multicast Service
MCE MBMS Coordination Entity
MME Mobility management entity
MT Mobile terminated
MTC Machine-Type Communications
PLMN Public Land Mobile Network
RAN Radio access network
SC-PTM Single Cell point-to-multipoint
SIB System information block
TA Tracking area
TAU Tracking area update
Tx Transmitter/Transmission
UE User equipment